Heat controlling device



Feb. 14, 1939. A A STRAND 2,147,321

HEAT CONTROLLING DEVICE Original Filed March 17, 1934 I 'f] 115 Z W 14 145 45 {"47 45 45 57 4g MM 9i;

ATTORN EYS Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE HEAT CONTROLLING DEVICE Application March 17,

Renewed 1 Claim.

The invention relates to heat controlling devices, and more particularly to special safety devices of the type used with oil burning heating furnaces and generally known as pyrostats.

The objects of the invention include the provision of a relatively inexpensive, dependable, highly efficient and sensitive device of the type above indicated.

Various further and more specific objects, features and advantages will clearly appear from the detailed description given below, taken in connection with the accompanying drawing which forms a part of this specification and illustrate, merely by way of example, embodiments .of the invention.

In the drawing:

Fig. 1 is a section taken through the pyrostat;

Fig. 2 is. a section taken on the line 2--2 of Fig. 1;

Fig. 3 is a section through the smoke stack of the oil burning furnace; and

Fig. 4 is a wiring diagram illustrating diagrammatically the relation of the pyrostat, the thermostat and the oil burning equipment.

In the following description and in the claim, various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will permit.

Like reference characters denote like parts in the several figures of the drawing.

In the drawing accompanying and forming part of this specification, certain specific disclosure of the invention is made for purposes of explanation, but it will be understood that the details may be modified in various respects without departure from the broad aspect of the invention.

Referring now to the drawing, and more particularly to Figs. 1 and 2, the regulating equip- ,ment, sometimes known as a pyrostat, is installed for the most part in a box denoted in general by Ill. The box comprises a metal body II and a pair of removable metal covers l2 and 13. Installed within the box is an insulating panel M on which is mounted the safety timing device I5, which determines the permissible time in which the oil burner must start, the clutch and switch indicated by [1 controlled by stack coil .IB, and starting relay l8. In general, the switches and relays are mounted on one side of the panel M with the connections and binding posts on the other side of the panel.

For mounting the pyrostat box, a hole is cut in the flue adjacent the oil burning furnace and the pyrostat box is mounted in a manner illus- 1934, Serial No. 716,058 July 9, 1938 trated particularly in Figs. 1 and 3. The box may be mounted either on a vertical or hori-- zontal portion of the flue. In the form indicated, the box is mounted on a horizontal portion of the flue, indicated by 20. If the flue 20 were vertical, it would merely be necessary to turn the box Hi 90, as will be understood by those skilled in the art.

The hole in the stack flue 20 is indicated by 2! and a plate 22 provided with hooks 23 is fitted to the curvature of the stack 20. A two-part strap 24 having hooks which engage the hooks 23 and having a pair of ears 25 through which the tightening bolt 23 passes, firmly clamps the box to the flue. It will be understood that the plate 22 is curved to fit the particular curvature of the flue and the strap 24 is cut to fit the circumference of the flue.

A hollow sleeve 21 passes through the plate 22 and has a large nut 29 and a small nut 28 firmly clamped against the plate 22. Lock nut 30 is provided to insure locking of the assembly. The sleeve 21 projects from the plate 22 and passes through a hole in the wall of the box'body I l and has a pair of nuts 3| for clamping the box body to the sleeve.

Passing through the sleeve 21 and free to rotate therein is a rod 32 having a toothed wheel 33 pinned thereto, as indicated in Fig. 1. Rod 32 also has a pin 34 engaging the end of sleeve 21 for holding the rod 32 in axial position.

The stack coil I6 is made of suitable bi-metallic material, as is Well known in the art, and one end is secured to nut 29 by set screw I29 and the other end is secured to the rod 32 by another set screw, as indicated in Fig. 3. Thus, the raising and lowering of the temperature in the stack winds and unwinds the stack coil, causing rotation of the control rod 32.

Referring now to the stack switch and clutch H, the toothed wheel 33 cooperates with a yieldable strap 35 mounted on an insulating bar 36. The strap 35 has a finger I35 which engages in the notches of the notched wheel 33 so that rotation of the wheel 33 operates the switch contacts 39.

The stack switch comprises a switch frame 31 suitably bolted to the insulating panel I4' and having opposed ears 90 and 9|, each of which has small recesses. Seated in these recesses are switch elements 38 and 40 connected by coil spring 4| which furnishes the toggle action and also holds the switch elements in their depressed seats. The switch element 40 is H-shaped, as indicated in Fig. 1, and carries the insulating block 36. The switch element 38 is U-shaped and carries the spring contacts 39 engageable with stationary contacts 92 and 93.

Thus, when the stack begins to cool, a small rotation of the toothed wheel 33 in the direction of the arrow operates to throw the toggle switch, causing the contacts 39 to close with a snap action. Further rotation of the toothed wheel 33, caused by further cooling of the stack, merely causes the spring finger I35 to yield and engage succeeding teeth of the toothed wheel. When the stack begins to heat up, a small rotation of the toothed wheel 33 in the opposite direction will then cause the contacts 39 to open with a snap action. Further rotation of the toothed wheel 33, caused by further heating of the stack, merely causes the spring finger I35 to yield and slide over the toothed wheel as during cooling of the stack.

Referring now to the safety timing device I5, this device is for the purpose of giving the oil burner a given time in which to start the fire. If the fire does not start, say within seconds, the safety device turns off the oil burner and its starting apparatus.

The safety timing device I5 comprises, in general, an asbestos insulatingmandrel 45 mounted in a pair of square asbestos blocks 46 and having a coil of resistance wire-41 wound thereon. A bi-metallic strip 48 is anchored to'a fixture I46 fixedly secured to the insulating base I4 and carries a piece of insulation 49. The heating coil 4'1" and bi-metallic strip 48 is enclosed in a boxlike housing H5 screwed to the insulating base and through which projects the insulating piece 49.

The operation of the safety timing device I5 opens the contacts 53, 59 and closes the contacts 54, 60. The former removes power from the oil burning equipment and the latter operates a buzzer 11 located at a convenient place to call attention to the fact that the oil burner did not start.

The spring contact 53 is anchored at one end by bracket I60 to the insulating base I4 and normally tends to take a position with the contacts 53, 59 open.

Upward movement of the spring contact 53 engages an insulating plate BI which causes leaf spring 54 to engage contact 60 to ring the buzzer. Spring member 53 is held down, however, by a latch 52 pivoted at I52and locked-by trigger 5I pivoted at I5I. A rod 51 passes through trigger 5I and through insulating piece 49 and a coil spring 58 surrounds rod 57.

For manually starting the oil burner after the oil burner has failed to start and the timing device has been operated, a push-button 55 is provided. The push-button passes through the wall of the box body I I and engages a leaf spring I55 carrying an insulating finger 50 which engages the catch 52 to reset the pyrostat.

Thus, when electric energy is applied to the heating coil 41, the bi-metallic strip 48 is heated and moves slowly upwardly. At the end of the permissible period, say 90 seconds, it has moved upwardly sufficiently to lift the trigger 5|, releasing catch 52 and causing the spring contact 53 to break with contact 59 and. causing engagement of contacts 54 and 66.

The attendant hearing the buzzer knows that the oil burner failed to start. He then pushes the push-button 55 which causes insulating plate 50 to engage the cam surface I50 of the catch 52, causing the latter to seat within the angle seat I53 of the trigger 5|. Setting of catch 52 causes contacts 53, 59 to make and contacts 54, 60 to break.

Referring now to the starting relay I8, this relay comprises a coil 65 wound on an insulating sleeve 66 which is secured to a brass supporting angle 86 secured to the insulating base I4. Within the insulating sleeve 66 is an iron bushing I66. The armature of the relay comprises a rod 61 having a magnetic armature piece 68 which has a brass guide strap II secured thereto which is adapted to slide along the surface of insulating base I4 to keep the relay armature in'proper position.

At the top of the armature rod 61 is an insulating piece 69 which supports a spring strap 10 engaging contacts I2. When current passes through winding 65, the iron armature 68 moves upwardly, closing contacts I0 and I2.

Referring now to Fig. 4, which discloses the wiring-diagram, similar reference characters are used as far as possible to indicate corresponding parts. The thermostat, which may be of the low voltage type, is mounted in a part of the building it is desired to keep at constant temperature and is connected in circuit with a step-down transformer I8, a relay I6 and a safetystat-I5.

The safetystat may be mounted on the furnace and may be an aquastat in the case of a hot water heating system, a pressurestat in the case of a steam heatingsystemor another thermostat in the-case of a'hot air heating system. The safetystat is normally closed and plays no part in the ordinary operation of the temperature control but only operates under abnormal conditions, as will be understood by those skilled in the art.

The buzzer I1, or other alarm, is located in a convenient part of thebuilding and may operate on the full volt alternating current. If a low voltage buzzer-is desired, obviously, a step-down transformer similar to transformer I8 may be interposed between the buzzer I1 and the A. C. line.

In the form shown, the oil burning equipment may include a motor,'an oil valve and an ignition device, as indicated. The particular construction of this equipment forms no part of the present invention and-will vary with the different types of oil burning systems. For example, the motor may operate an air fan for supplying. air for combustion. In some cases, no oil valve is required, but when one isprovided, it is automatically opened at the same time the motor is started. The ignition device will supply a hot spark for igniting the combustible mixture of oil and air.

It will be understood that any type of thermostat maybe used with this pyrostat equipment. The thermostat shown is a low voltage thermostat operable on, say, 14 volts. The present pyrostat may also'operate with a 110 volt thermostat of the type disclosed in copending application Serial No. 569,916, filedOctober 20, 1931.

To substitute 'the 110 volt thermostat of the copending application, the low voltage thermostat and transformer 18 ofthe present case will be omitted, and for simplicityof description, the safetystat I5 and its relay I6 will also be assumed to be omitted. The terminals '3 andC of the pyrostat will be substituted for the load in Fig. 10 of the copending application with the terminal B connected directly-to the 110 volt power source. The buzzer 1! may, of course, be connected to the terminal A and to the opposite side of the power source from B, as will be understood by those skilled in the art. This makes the entireheat control system a 110 volt system.

7 Operation Referring to Fig. 4, assume the oil burner is out and the temperature of the room in which the thermostat is located is above the temperature at which the thermostat contacts will close. The following will then be the condition of the pyrostat: The stack contacts 39 are closed, the safety contacts 59 are closed, starting relay contacts 12 are open, the. main thermostat contacts are open, the contacts of relay 1B are open and. the contacts of safetystat 15 are closed.

When the temperature of the room drops to the set temperature, main thermostat contacts close, applying energy to the relay [6, closing its contacts, and applying energy to the safety heating coil 41, ignition and starting relay l8. The starting relay l8 operates, closing contacts 12 which applies voltage to the motor and oil valve. The starting relay l8 then locks itself in. If the fire starts up before the safety device [5 operates, the heat in the stack causes the stack coil It to turn the rod 32 in the opposite direction to the arrow in Fig. 2, opening the stack contacts 39, thereby removing voltage from the ignition and from the safety timing device I5.

The oil burner continues to burn until the temperature of the room goes above set temperature when the thermostat contacts open, causing contacts of relay 16 to open, removing energy from the motor and oil valve and unlocking the starting relay l8, opening contacts 12. The oil burner goes out and, as soon as the stack cools only a small amount, the rotation of the rod 32 in the direction of the arrow in Fig. 2 closes the stack contacts 39. The closing of the stack contacts 39 by a small temperature drop in the flue places the apparatus almost immediately in readiness to start the oil burner should the temperature of the room drop below the set temperature, and it is not necessary to wait until the stack cools down to place the apparatus in readiness to start.

If for any reason the oil burner does not start up within the time limit of the safety timing device I4, say, within seconds, the upward movement of the bi-metallic strip 48 raises trigger 5i, releasing catch 52 and permitting the spring contact 53 to break with contact 59, removing voltage from the. motor, oil valve, ignition and safety timing device 14. The upward movement of spring contact 53 closes contacts 54 and 69, causing the buzzer 11 to ring, calling attention to the fact that the oil burner did not start.

The attendant upon hearing the buzzer presses the push-button 55 which closes contacts 53 and 59, opening the buzzer contacts 60 and 54.

Closing of the main contacts 59 and 53 applies voltage to the motor, oil valve and ignition as well as to the safety timing device l4. If the fire does not start within, say, 90 seconds, the safety timing device 14 will again operate, opening contacts 53, 59 and closing contacts 54, 60 to again call attention to the fact that the oil burner failed to start.

If the electric power should fail when the temperature of the room is above the set temperature, nothing will happen since there is no power on the pyrostat system. If the electric power should fail when the temperature of the room is below the set temperature and the thermostat is calling for heat, the contacts of relay [6 open, contacts of the starting relay l8 open, and power is removed from. the motor and oil valve causing the fire to go out.

As soon as the electric power goes on, contacts of relay 16 close and the system again starts up in the regular way, providing the stack contacts 39 are closed. If the electric power had not been off for sufficient time to cause the stack to cool off and thereby close the stack contacts 39, the oil burner will not start up until the stack does cool off sufficiently to close contacts 39.

It should be noted that the stack contacts 39 open directly as soon as the fire starts and then close directly as soon as the fire stops and the stack temperature drops a small amount. If for any reason the fire should go out for a short interval, either because the electric power fails or because the house is overheated for a short period from some other source, such as from a kitchen oven, the system does not have to Wait until the stack gets cold for the fire to start.

In case of fiame failure, due to water in the oil (With motor going and the oil valve open) a small drop in temperature in the stack closes the stack contacts, turning on the ignition and putting power on the safety timing device [4. If the fire does not start within the time limit of the safety device M, the safety contacts 53, 59 open and the ignition is turned off, the motor stops, the oil valve closes, starting relay l9 releases and the buzzer l! rings.

Whenever the fire does not start (or restart in case of temporary failure of flame due to any cause) after the time set when the ignition is turned on, the safety device I4 operates to shut down the oil burning system and to ring the buzzer. The attendant must press the pushbutton 55 Which resets the safety timing device [5 and the system restarts in the regular way, as above described. If the oil burner refuses to start after a number of repeated attempts by pushing push-button 55 something is wrong and repairs must be made to the system.

Thus, a pyrostat system has been described which is relatively simple, is made of inexpensive parts and is very easy to assemble. The system takes care of failure of the fire to start within a predetermined period. It takes care of failure of the electric power. As soon as the fire goes out, the stack only has to cool a relatively small degree to place the system in condition for restarting when the thermostat calls for heat.

It will be understood that the alarm illustrated by the buzzer 71 may be any kind of an audible or visible alarm. Furthermore, it will be understood that the pyrostat may be mounted in any part of the furnace where it will be subject to the heat of the flame, as for example, in the fire door as well as in the flue, as illustrated. Furthermore, it will be understood that the safetystat 15 may be located in the volt side, for example, between the point C and the relay 16 on the low voltage thermostat control, if desired.

While certain novel features of the invention have been disclosed and are pointed out in the annexed claim, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

In a system for controlling oil burners or the like having a control switch, a starting relay comprising a solenoid and a pair of starting contacts, a stack switch having a pair of stack contacts and a bridging member, a safety heating device saidwcontrol switch and said safety switch, said ignition device being connected between said safety switch and a, point between said heating coil and said stack contacts, said solenoid being connected to the bridging member of said stack switch and to said safety switch, and an interconnection between said bridging member and a point in said first circuit between the starting contacts and said fuel-feeding device.

AUGUST A. STRAND. 

